NOTE: This activity is based on one developed by OMSI for their hands-on chemistry lab.
This activity works well as an extension of Solids and Liquids (Grade 2) or Mixtures and Solutions (Grade 5). It can also be used as a hands-on assessment with these kits.
Typical Duration: unknown.
Overview: Students separate recyclable materials based on their properties.
Plastic: Floats on water and is not attracted to a magnet.
Aluminum: Sinks in water and is not attracted to a magnet.
Iron: Sinks in water and is attracted to a magnet.
Preparation
Students may work as groups, pairs, or individuals on this lesson. Be sure to have enough materials for whichever you choose. Each group will need:
A mixture of:
Plastic: Cut up plastic soda bottles into ~1"x1" squares.
Aluminum: Cut up aluminum cans (or tear aluminum foil) into ~1"x1" sqares.
Steel: Cut up steel cans into ~1"x1" squares, or just add old steel nuts and washers to the mix. (Don't add sharp items like screws and nails!)
A magnet (you can use the ring magnets in the magnets and motors kit if you have access to them).
A bowl of water
A strainer (can be a kitchen strainer, a wire screen (such as provided in the Mixtures and Solutions or Solids and Liquids kits), an aquarium net, etc.).
SAFETY: Metal scraps are SHARP! Be careful not to cut or poke yourself.
Procedure:
Students use a magnet to pick out the steel scraps.
Students add the mixture to water. The metal scraps sink while the plastic floats. Students skim off the plastic with the strainer.
Advice
If the students have done a similar investigation already (such as Mixtures and Solutions Inv. 1.4 or Solids and Liquids Inv. 3.2), give them as little of a hint as necessary.
The steps in the procedure can be done in any order. It is best to get the students to design their own procedure. This may include other steps, such as stirring, drying, etc.
You can use this with a unit on recycling.
If your school or town has recycling service, discuss how the recycling is separated or commingled there. How could you easily separate these things?
Discuss what happens once the recycling is sorted. How are these materials turned into other things?
Is it easier for the consumer to use commingled recycling, or to separate all the materials before they get picked up?
Slideshow (.pdf) on all recyclables and how to prepare them for recycling.
Extensions
Encourage students to think of other recyclable items, and how they might separate them from a mixture. For example, paper is sometimes separated by blowing it out with a fan. Avoid using glass, as this can break and cut students.
This activity works well as an extension of Solids and Liquids (Grade 2) or Mixtures and Solutions (Grade 5). It can also be used as a hands-on assessment with these kits.
Typical Duration: unknown.